A call center is a central place where customer and other telephone calls are handled by an organization, usually with some amount of computer automation. Typically, a call center has the ability to handle a considerable volume of calls at the same time, to screen calls and forward them to someone qualified to handle them, and to log calls. Call centers are used by mail-order catalog organizations, telemarketing companies, computer product help desks, and any large organization that uses the telephone to sell or service products and services.
A call center typically comprises a plurality of human operators, each using a telephone to converse with a respective customer who has placed a call. When a caller places a call, the caller is automatically routed to an operator who is not currently engaged in a conversation with another caller. If all operators are busy, the caller is usually placed “on hold” and hears some variation of the following: “All operators are currently assisting other customers. Please stay on the line and the next available operator will take your call. Calls are answered in the order that they are received”.
Call centers typically comprise one or more roaming human supervisors who might bridge into a conversation between an operator and a caller (i.e., the supervisor “gets on the line”). Scenario examples in which a supervisor might bridge into a conversation include:                the supervisor wishes to monitor the conduct of the operator;        the supervisor listens to verify that a caller has authorized a particular action;        the caller is frustrated with the operator and requests to speak with a supervisor.        
A supervisor typically walks around the call center carrying a telephone headset and bridges into a conversation by walking to the corresponding operator's position and physically inserting a plug from the headset into a jack in the operator's telephone. Inserting the plug enables a three-way conversation between the supervisor, operator and caller, and removing the plug reverts to a two-way conversation between the operator and caller.
Some call centers have multiple supervisors, wherein each supervisor (i) is responsible for supervising a different non-empty subset of the operators, and (ii) bridges only into conversations involving these operators.
The need of the supervisor to continually insert and remove his or her headset's plug can be inconvenient for the supervisors, and can also cause the plugs to break prematurely. In addition, prior art systems generally lack an automated security mechanism to prevent a supervisor from bridging into a conversation for which he/she is not authorized. Therefore, the need exists for a call center apparatus that overcomes these disadvantages.